The invention relates to digital energy meters.
A known approach for measuring the energy in a waveform is to multiply the voltage and current components of the waveform by analog means and transform the product into a digital value by a voltage-to-frequency converter. Examples of this approach are disclosed in U.S. Pat. Nos. 3,718,860; 4,079,313; and 4,360,879. One problem with these approaches is the drift in the analog devices.
Another known approach is to convert the respective voltage and current components into digital form for processing through a computationally intense algorithm in a microprocessor. Examples of this approach are disclosed in U.S. Pat. No. 4,345,311 and IEEE Paper (Volume IE-29, No. 1, February 1982) entitled "A Wide-Range Digital Power/Energy Meter for Systems with Nonsinusoidal Waveforms". A problem with these approaches is the complexity of the computations required to obtain a measurement of energy.